By his great reputation and his strong magnetic power, Dr. Cartwright dissipated the fears of those around him, and prevented an epidemic. For this grand appreciation and successful application of a principle--the power of mind and thought over physical conditions, a power just dawning on the perception of the race--he deserves a nobler monument than any we have accorded to heroes and statesmen. The sanitarians of the present day would think on the contrary that Dr. Cartwright was worthy of condemnation and imprisonment. Dr. Cartwright, however, honestly believed that yellow fever was not a contagious disease. At that time the non-contagionists were numerous, learned, experienced, and respectable. The contagionists, however, finally carried the day in the face of innumerable evidences of non-contagion, which, strangely enough, have now about ceased to exist. Whether they transformed a non-contagious into a contagious disease by repeated and violent asseverations, which played upon and hypnotized the professional and public mind, is a subtle point for psychological investigation, not likely to be made by the present generation of doctors. Can a non-contagious disease become contagious by mental action? The power of fear to modify the currents of the blood and all the secretions, to whiten the hair, to paralyze the nervous system, and even to produce death is well known. Its power to impress organic changes upon the child in the womb through the mother's mind is well established. When yellow fever is reported about and believed to be imminent and contagious, fear, combined with a vivid imagination of the horrors and woes of the pest, can precipitate sickness which will take on the form and color present to the thought, and yellow fever may spread rapidly from person to person, all through the medium of the mind. "Everything," said a great philosopher, "was at first a thought."